Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 858 · 40 questions

How to do it in your head (Round up, add back): Round the number you take away up to the next ten or hundred: 297 → 300 (3 too many). Take away the round number. Add back the extra, because you took away too much.

1. 1.678 − 299 =
2. 2.760 − 198 =
3. 3.815 − 298 =
4. 4.922 − 627 =
5. 5.368 − 198 =
6. 6.674 − 597 =
7. 7.998 − 597 =
8. 8.979 − 598 =
9. 9.977 − 587 =
10. 10.396 − 199 =
11. 11.942 − 649 =
12. 12.444 − 199 =
13. 13.286 − 197 =
14. 14.746 − 299 =
15. 15.879 − 298 =
16. 16.720 − 298 =
17. 17.981 − 298 =
18. 18.651 − 419 =
19. 19.617 − 529 =
20. 20.897 − 488 =
21. 21.776 − 498 =
22. 22.974 − 398 =
23. 23.317 − 279 =
24. 24.910 − 597 =
25. 25.860 − 799 =
26. 26.687 − 619 =
27. 27.661 − 197 =
28. 28.183 − 139 =
29. 29.866 − 178 =
30. 30.893 − 798 =
31. 31.842 − 397 =
32. 32.770 − 138 =
33. 33.793 − 499 =
34. 34.897 − 297 =
35. 35.910 − 797 =
36. 36.815 − 528 =
37. 37.958 − 697 =
38. 38.795 − 567 =
39. 39.575 − 397 =
40. 40.887 − 397 =

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